Physics - Particle Model of Matter

solids

-particles very close together
-arranged in regular pattern
-vibrate in fixed position

liquids

-particles very close together
-not arranged in regular pattern
-particles can move around each other

gases

-particles very far apart
-not arranged in any pattern
-particles moving very rapidly

density

the density of a material tells us the mass for a given volume

density formula

density (kg/m³) = mass (kg) / volume (m³)

energy in particles

-kinetic when moving
-potential = intermolecular bonds + chemical bonds

internal energy

-energy stored in a system by particles
-total kinetic energy + potential energy of all the particles that make up the system

sublimation

-solid turning directly into a gas

when changes of state take place…

mass is always conserved

changes of state are…

physical changes, if we reverse the change: material recovers its original properties

specific heat capacity

amount of energy required to raise the temperature of 1kg of the substance by 1°C

specific heat capacity formula

change in thermal energy (j) = mass (kg) x specific heat capacity (j/kg) x change in temperature (°C)

Describe and explain a heating curve.

-temp of solid rising as we increase kinetic energy of particles
-at some point temp stop increasing + line becomes horizontal.
-internal energy and potential energy increases
-at this point solid turning to a liquid (melting) because energy is weakening/breaking forces of attraction between particles
-temp rises again
-line flattens/becomes horizontal again, boiling at this point and turns to gas

during the changing of state…

potential energy increases, kinetic energy stays the same. Temperature does not increase.

specific latent heat

amount of energy required to change the state of 1kg of the substance with no change in temperature

specific latent heat of fusion

amount of energy required to change 1kg of a substance from a solid to a liquid with no change in temperature

specific latent heat of vaporisation

amount of energy required to change 1kg of a substance from a liquid to a gas with no change in temperature

Solid

The state of matter where the particles are linked by strong forces. They are packed closely together and move very little. The particles usually form a regular and specific pattern.

Liquid

The state of matter where the particles have weaker bonds. They are still tightly packed but may move around each other.

Gas

The state of matter where particles are far apart and are in constant random motion. There is no interactive between the particles.

Melting Point

The temperature at which a solid turns into a liquid .

Boiling Point

The temperature at which a liquid turns into a gas.

Melting

When a solid changes to a liquid.

Boiling

When a liquid changes a gas at the boiling point

Evaporating

When a liquid changes to a gas below the boiling point

Condensing

When a gas changes to a liquid.

Sublimating

When a solid changes to a gas.

Physical Change

A change that does not produce a new substance. If the change is reversed the substance recovers its original properties.

Internal Energy

The total energy in the kinetic and potential stores of all the particles (atoms and molecules) that make up a system.

Specific Heat Capacity

The amount of energy required to raise the temperature of one kilogram of a substance by one degree Celsius. Often represented by the symbol 'c'. Its unit it J/kg°C.

Kinetic Theory

The theory that explains the different states of matter (solid, liquid and gas) by the arrangement and energies of their particles.

Metres cubed (m³)

The unit of volume.

Density

The mass per unit volume of a material. It can be thought of as representing how tightly packed the particles are within the material. Often represented by 'ρ'. The unit of density is kg/m³.

kg/m³

The standard unit of density.

Kinetic Theory Of Matter

Particle model of solids, liquids and gases which describes their properties.

States Of Matter

A form that substances take (e.g. solid, liquid and gas).

Change Of State

When a substance changes from one state of matter to another (e.g. a solid changing into a liquid).

Degrees Celsius (°C)

The unit of temperature and temperature change.

Heating Curve

A graph which shows how the temperature of a substance changes as it is heated.

Cooling Curve

A graph which shows how the temperature of a substance changes as it is cooled.

The amount of matter in a given volume

Density

What equation links density, mass and volume?

Density (kg/m3) = m(kg)/volume(m3)

Which state of matter is most dense?

Solids

Which state of matter is least dense?

Gases

How can you measure the volume of an irregular object?

By putting it in a eureka can full of water and seeing the volume it displaces

How do you measure the volume of a regular object?

Using a ruler, micrometer or Vernier callipers

What is a physical change?

A change which is reversible, for example a change of state. The chemical make up is unchanged.

What is a chemical change?

A change in which chemical bonds are broken and reformed to form new products

Energy stored inside a system by the particles that make up the system

Internal energy

What makes up internal energy?

The total kinetic energy and stored energy of particles within the system

How can increasing the heat of a system impact the internal energy?

It increases the energy stored, either raising the temperature of a system (kinetic) or causing a change of state (potential)

What is the unit of specific heat capacity?

J/kgoC

What is the unit for energy?

Joules (J)

What is the unit for mass?

kg

What is shown by a flat point on a temperature vs time graph when heating a substance?

The change of state

How do particles move in gases and liquids?

randomly

How is the temperature of a gas related to the average kinetic energy of molecules?

The greater the temperature the more kinetic energy carried by particles

Kinetic energy

Shown on a heating curve by a diagonal line (increasing temperature as particles are moving faster)

Potential energy

Shown on a heating curve as a horizontal line (Energy goes into separating forces between particles as it changes state)